Recently, ionic liquid solvents, as novel “green” solvents, have been widely applied to fields of separation, catalysis, gas absorption and so on, and become ideal solvents for gas purification, due to their advantages such as good reusability, low volatility, less pollution, low energy consumption, adjustable structures and properties, superior physical and chemical stability, and environmental friendliness.
Currently, most absorbents used for purifying gases such as carbon dioxide are alkylolamine compounds or mixtures thereof, which are accompanied with many shortages, e.g. high energy consumption, great loss of absorbents caused by volatilization, and the like. And purification of gases such as carbon dioxide with a conventional ionic liquid alone may also cause the problems such as a high viscosity of the solvent and a low transfer efficiency, etc. Thereby, it is necessary to develop an ionic liquid solvent that has a low viscosity; is suitable for purifying gases such as carbon dioxide, sulfur dioxide, hydrogen chloride, hydrogen sulfide, etc.; has a great absorption capability and is more easy for the desorption of absorbed gases than the traditional processes; and has a low energy consumption, a high stability and a high reusability.